Microbleeds and cavernomas after radiotherapy for paediatric primary brain tumours
Introduction
The overall survival of childhood primary central nervous system tumours (PCNST) increased in the last decades [1]. As this population ages, new challenges will rise to health care providers, with emphasis on the diagnosis and management of late sequelae from treatment, including radiation-induced cerebrovascular damage [2]. Microbleeds and cavernomas can be grouped as focal hemosiderin deposition (FHD) [3] and are imaging markers of radiation-induced small vessel disease (SVD) [4]. Both are best detected using either susceptibility-weighted imaging (SWI) or T2*-weighted gradient-recalled echo (GRE) sequences [3], [5]. Microbleeds are also associated with cognitive impairment in the general population [5], [6], [7] and very recently, were found to be associated with neurocognitive dysfunction in PCNST survivors after radiotherapy (RT) [8]. The underling mechanism between RT and the occurrence of FHD is not yet fully understood. The purpose of the present study was to depict, quantify and locate FHD lesions, and to correlate its occurrence with the type, and topographic location of RT in childhood PCNST patients.
Section snippets
Study population
All paediatric patients with central nervous system tumours followed in our neuro-oncology unit from January 1973 to August 2015 were reviewed. Patients with at least 1 GRE sequence acquisition in our hospital's medical image database were included (this MRI sequence was introduced in our imaging protocol in 2006).
Data collection
All patients were regularly followed in a dedicated outpatient consultation, with at least one visit each year and at least one brain MRI each year. Data on demographic information
Results
Of the 579 paediatric patients with PCNST of our institutional database, 190 had at least one brain GRE imaging during the follow-up period. One-hundred and nine (57.3%) were male. The mean age at the diagnosis of PCNST was 8.2 years (range 0–16 years) and 7.5 years (range 0–15 years) for the RT treated (n = 132) and non-RT treated group (n = 58) respectively. The median follow-up period was 133.0 months, with 15,005.0 patient-years of follow-up. Embryonal (42.4%), ependymal (17.4%) and low grade
Discussion
In this large cohort of childhood PCNST, we have shown that FHD lesions, namely microbleeds and cavernomas, occurred exclusively in childhood PCNST patients treated with RT. In our analysis, we used the current international definitions for microbleeds and cavernomas [6], [10] and grouped them under a broader designation (FHD), which covers a spectrum of imaging changes that are closely related [4]. FHD lesions occurred in a high percentage (41.6%) of PCNST patients treated with RT. We
Authors' contribution
Conception and design: João Passos; Sofia Nunes; Hipólito Nzwalo
Acquisition of data: Sofia Nunes; João Passos; Joana Marques; Mariana Valente; António Mota
Analysis and interpretation of MRI sequences: Alexandra Borges; Ana Azevedo; Sofia Nunes; João Passos
Statistical analysis: Sofia Nunes
Article drafting: João Passos; Hipólito Nzwalo; Sofia Nunes
Article review and final approval: all authors
Disclosure
The authors have nothing to disclose.
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